Switches, e.g. switched transistors, are used in various applications such as switched-mode power supplies. The switches in such applications are typically controlled using a control circuit which is configured to control the switch such that the switch alternates between an on-state (where the switch is conducting or closed) and an off-state (where the switch is blocking or open) according to a commutation cycle rate. A commutation cycle typically comprises one period where the switch is in on-state and one period where the switch is in off-state. A duty cycle of the switch is typically defined as the ratio of the length of the period where the switch is in on-state and the length of the commutation cycle.
The control circuit of the switch may be configured to control the commutation cycle rate and/or the duty cycle of the switch. In this context, it may be beneficial to provide the control circuit with information regarding the current flowing through the switch (e.g. regarding the drain-to-source current flowing through a switched transistor). For this purpose, the control circuit may comprise a current sensing pin which is configured to be coupled to appropriate current sensing means (e.g. a shunt resistor) at the switch.
The use of a dedicated current sensing pin is, however, disadvantageous, because an additional pin typically renders the design of the control circuit more complicated and increases the cost of the control circuit. It is therefore desirable to provide information regarding the current through the switch without the need of a dedicated current sensing pin.